with \( f \) is the *decay constant* of the axionic inflaton. For \( f \sim 0.05 \, M_{\text{Pl}} \) (typical in wire theory), obtained \( r \sim 0.00075 \).
Comparison with Other Models:
| Inflation Model | Prediction \( r \) | Origins |
| Chaotic (\( m^2\phi^2 \)) | \( \sim 0.1 \) | Potensial kuadratik | Starobinsky | \( \sim 0.003 \) | \( R^2 \)-gravity |
| String Theory (KKLT) | \( \mathbf{\sim 0.003} \) | Stabilization moduli |
4.1.2 Non-Gaussianities (\( f_{\text{NL}} \))
The interaction of the inflaton with other fields (e.g. *volume modulus*) results in non-Gaussianity:
\[f_{\text{NL}} \sim \mathcal{O}(1) \quad \text{(orthogonal type)},\]
different from the simple single-field model (\( f_{\text{NL}} \sim \mathcal{O}(0.01) \)).
Detection:
- Planck 2018: \( f_{\text{NL}}^{\text{ortho}} = -26 \pm 47 \) (68% CL).
